1. Field of the Invention
The present invention relates to an imaging system and more specifically to a method and apparatus of developing a latent magnetic image.
2. Discussion of Related Art
U.S. Pat. No. 4,368,687 describes a method and apparatus for developing a latent magnetic image, in which a uniform, very thin layer of an electrostatically charged insulating and magnetically attractable toner powder is applied to a toner conveyor and the thin layer of toner powder is fed to a developing zone where it is brought to a distance of 200 to 400 micrometers from the image-carrying medium. To complete the image development, an AC voltage is applied in the developing zone between the toner conveyor and the image-carrying medium.
In comparison with other known developing methods in which magnetically attractable toner powder is brought into (frictional) contact with an image-carrying medium in a developing zone, the method according to the instant U.S. patent has the advantage that background resulting from the deposition of toner particles on the image-free parts of the medium is prevented. A disadvantage of this method, however, is that the apparatus for performing the method must satisfy high accuracy requirements to achieve the required slit width such that the apparatus parameters must be strictly adhered to. In addition, thin toner layers have to be used in this method so that during the development of images with high information density, such as large black areas, the disadvantage may arise such that the toner supply in the developing zone may be too low and the developed images consequently have an inadequate density.